Office machines for processing text data to produce hard copies are being utilized with increasing frequency for data processing. Such text processing machines are physically structured to include all the necessary elements for data processing including a display screen for presenting to an operator a visual presentation of record data as it will appear on hard copy or be utilized by an output device. Typically, text processing machines incorporate a conventional typewriter keyboard with additional control keys for operator interface with the system controls. For data processing, operator instruction are input through the keyboard and displayed on a screen in a manner similar to the use of such machines for text processing. The display is segmented to allow data formatting instructions to be presented to the operator along with a visual presentation of the data records being processed. Thus, the display not only provides a visual presentation to the operator of the record data being processed, but also provides prompting instructions to allow interface between the text processing machine and the data operator.
Text processing machines on which data processing is carried out include electronic hardware programmed to evaluate operator keystrokes and to control the display. This electronic hardware includes memory for storing file format information and instruction data for future use for processing the file records for subsequent utilization or preparation of hard copy. Responding to the keystrokes of an operator are system controls including programmed computers which prepare the display screen for displaying to the operator file record data. Ease of operation of the machine for the operator is in large part determined by the electronics and associated computers and programs therefor.
Data processing on a text processing machine is achievable by utilization of algorithms with the machine's computers and memory. There are, however, several differences between the processing of text data and record data in a text processing machine. Typically, text is stored in an unstructured, but formatted, format while file records are stored in a structured, but unformatted manner. Text data is formatted in that it includes tabs, carrier returns, etc. Due to the fact that a data file can be fairly large, structuring of the included data permits rapid access to any particular portion. However, this requires programming to achieve this rapid access. To assist an operator in the accessing of file record data, the system display screen is segmented into virtual displays or frames that includes grids to be filled in by an operator for processing of the file data. Through keying, an operator can then cause the stored record data to be qualified for keying "search" criteria.
File record data processing in text processing machines usually utilizes storage of the file record data on a disk. In the past, sorting of the data on the disk was carried out externally, that is, data was transferred from one disk to a second disk in a sort operation or sorting was completed in internal memory. With some earlier file record data processing in a text processing machine, a disk access is needed for the sorting of each record and therefore processing is too cumbersome and time consuming.
Sorting of data is one of the most utilized functions of a text processing machine as a data processor and it thus becomes important to provide efficiency and ease of operator interface of the sorting function.